Modifying the shape and color of hair is an important area of modern cosmetics. A consumer uses color-changing agents for fashionable hair style color schemes or for concealing gray, or even white, hair with fashionable or natural color tints. In addition to the desired coloration power, these agents should cause the least possible damage to the hair and preferably may even possess additional care characteristics.
There are a number of diverse dying systems for the provision of color-changing cosmetic agents, especially for hair. An oxidation dye is used for long-lasting, intensive colorations with corresponding fastness characteristics. Such dyes usually include oxidation dye precursors, “developer components,” and “coupler components.” Under the influence of oxidizing agents, or from atmospheric oxygen, the developer components form the actual colorants among each other or by coupling with one or more coupler components. In spite of their advantageous coloration properties, oxidative hair dyeing agents are afflicted with disadvantages for the user.
First, the use of these oxidizing agents for developing the actual coloration and the basic pH needed for dyeing damages the hair structure and the hair surface. However, there is still a need for agents with improved dyeing power. In particular, agents resulting in improved, uniform colorations with high intensity and vividness as well as a good gray coverage capability (in particular on differently treated hair) are a continued focus of development. As both the resultant coloration and the associated stress on the hair fibers depend on the contact time of the agent, there may exist a need to monitor the coloration progress during the dyeing procedure, such that the desired end point of the treatment can be exactly determined. Doing so may minimize stresses on the hair fibers in addition to improving the desired coloration result. It is also desirable to provide a transparent or clear dye preparation.
Finally, current hair dyes, due to the plurality of ingredients, have been shown to frequently possess unsatisfactory rheological properties. These are particularly evident from the viscosity fluctuations during storage and application. For example, agents that thicken during storage are associated with problems such as withdrawal, dosing, and application. Whereas agents that decrease in viscosity during storage have inadequate application characteristics.
Consequently, an object of the present specification is to mitigate the abovementioned disadvantages of oxidative hair dyes. By detecting the end point of the treatment, the dyes may cause less damage to the hair. In particular, protection against oxidative damage to the hair structure and hair surface are achieved by means of the hair dye. At the same time, the dye may possess improved rheological properties that, in particular, offer improved viscosity stability and shear sensitivity. In addition, the dye may enable improved color intensity and improved gray coverage compared with conventional dyes.
Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.